Programs & Examples On #Family tree

A family tree, or pedigree chart, is a chart representing family relationships in a conventional tree structure.

Cycles in family tree software

I hate commenting on such a screwed up situation, but the easiest way to not rejigger all of your invariants is to create a phantom vertex in your graph that acts as a proxy back to the incestuous dad.

Convert StreamReader to byte[]

You can also use CopyTo:

var ms = new MemoryStream();
yourStreamReader.BaseStream.CopyTo(ms); // blocking call till the end of the stream
ms.GetBuffer().CopyTo(yourArray, ms.Length);


var ms = new MemoryStream();
var ct = yourStreamReader.BaseStream.CopyToAsync(ms);
await ct;
ms.GetBuffer().CopyTo(yourArray, ms.Length);

Check if number is prime number

Using Soner's routine, but with a slight variation: we will run until i equals Math.Ceiling(Math.Sqrt(number)) that is the trick for the naive solution:

boolean isPrime(int number)
    if (number == 1) return false;
    if (number == 2) return true;

    var limit = Math.Ceiling(Math.Sqrt(number)); //hoisting the loop limit

    for (int i = 2; i <= limit; ++i)  
       if (number % i == 0)  
           return false;
    return true;


iPhone Safari Web App opens links in new window

The other solutions here either don't account for external links (that you probably want to open externally in Safari) or don't account for relative links (without the domain in them).

The html5 mobile-boilerplate project links to this gist which has a good discussion on the topic:

Here's the final code they came up with:

<script>(function(a,b,c){if(c in b&&b[c]){var d,e=a.location,f=/^(a|html)$/i;a.addEventListener("click",function(a){;while(!f.test(d.nodeName))d=d.parentNode;"href"in d&&(d.href.indexOf("http")||~d.href.indexOf(,e.href=d.href)},!1)}})(document,window.navigator,"standalone")</script>

How to generate classes from wsdl using Maven and wsimport?

Here is an example of how to generate classes from wsdl with jaxws maven plugin from a url or from a file location (from wsdl file location is commented).

<project xmlns="" xmlns:xsi="" xsi:schemaLocation="">
        <!-- usage of jax-ws maven plugin-->
                <!-- using wsdl from an url -->
                <!-- or using wsdls file directory -->
                    <!-- <wsdlDirectory>src/wsdl</wsdlDirectory> -->
                <!-- which wsdl file -->
                <!-- <wsdlFiles> -->
                    <!-- <wsdlFile>myWSDL.wsdl</wsdlFile> -->
                <!--</wsdlFiles> -->
                <!-- Keep generated files -->
                <!-- Package name --> 
                <!-- generated source files destination-->

What is the difference between null and undefined in JavaScript?

If a variable is not initialized then it is undefined. undefined is not a object. Example: var MyName; console.log(typeof MyName);

Check the console log in development tool, it will be printed as undefined.

null is a a object.If you want some variable to be null then null is used.null variable exists but value is not known.It should be assigned to a variable pro grammatically. null is not automatically initialized.

Example : var MyName = null; console.log(typeof MyName); Check the csole log in development tool, it will be an object.

Limit Decimal Places in Android EditText

Simpler solution without using regex:

import android.text.InputFilter;
import android.text.Spanned;

 * Input filter that limits the number of decimal digits that are allowed to be
 * entered.
public class DecimalDigitsInputFilter implements InputFilter {

  private final int decimalDigits;

   * Constructor.
   * @param decimalDigits maximum decimal digits
  public DecimalDigitsInputFilter(int decimalDigits) {
    this.decimalDigits = decimalDigits;

  public CharSequence filter(CharSequence source,
      int start,
      int end,
      Spanned dest,
      int dstart,
      int dend) {

    int dotPos = -1;
    int len = dest.length();
    for (int i = 0; i < len; i++) {
      char c = dest.charAt(i);
      if (c == '.' || c == ',') {
        dotPos = i;
    if (dotPos >= 0) {

      // protects against many dots
      if (source.equals(".") || source.equals(","))
          return "";
      // if the text is entered before the dot
      if (dend <= dotPos) {
        return null;
      if (len - dotPos > decimalDigits) {
        return "";

    return null;


To use:

editText.setFilters(new InputFilter[] {new DecimalDigitsInputFilter(2)});

How do I filter date range in DataTables?

Here is DataTable with Single DatePicker as "from" Date Filter


Here is DataTable with Two DatePickers for DateRange (To and From) Filter


PySpark: multiple conditions in when clause

when in pyspark multiple conditions can be built using &(for and) and | (for or).

Note:In pyspark t is important to enclose every expressions within parenthesis () that combine to form the condition

dataDF = spark.createDataFrame([(66, "a", "4"), 
                                (67, "a", "0"), 
                                (70, "b", "4"), 
                                (71, "d", "4")],
                                ("id", "code", "amt"))
       when((col("code") == "a") | (col("code") == "d"), "A")
      .when((col("code") == "b") & (col("amt") == "4"), "B")

In Spark Scala code (&&) or (||) conditions can be used within when function

val dataDF = Seq(
      (66, "a", "4"), (67, "a", "0"), (70, "b", "4"), (71, "d", "4"
      )).toDF("id", "code", "amt")
       when(col("code") === "a" || col("code") === "d", "A")
      .when(col("code") === "b" && col("amt") === "4", "B")


| id|code|amt|new_column|
| 66|   a|  4|         A|
| 67|   a|  0|         A|
| 70|   b|  4|         B|
| 71|   d|  4|         A|

This code snippet is copied from

Tick symbol in HTML/XHTML

The client machine needs a proper font that has a glyph for this character to display it. But Times New Roman doesn’t. Try Arial Unicode MS or Lucida Grande instead:

<span style="font-family: Arial Unicode MS, Lucida Grande">
    &#10003; &#10004;

This works for me on Windows XP in IE 5.5, IE 6.0, FF 3.0.6.

How to write a multidimensional array to a text file?

ndarray.tofile() should also work

e.g. if your array is called a:

a.tofile('yourfile.txt',sep=" ",format="%s")

Not sure how to get newline formatting though.

Edit (credit Kevin J. Black's comment here):

Since version 1.5.0, np.tofile() takes an optional parameter newline='\n' to allow multi-line output.

Angular cli generate a service and include the provider in one step

Add a service to the Angular 4 app using Angular CLI

An Angular 2 service is simply a javascript function along with it's associated properties and methods, that can be included (via dependency injection) into Angular 2 components.

To add a new Angular 4 service to the app, use the command ng g service serviceName. On creation of the service, the Angular CLI shows an error:

WARNING Service is generated but not provided, it must be provided to be used

To solve this, we need to provide the service reference to the src\app\app.module.ts inside providers input of @NgModule method.

Initially, the default code in the service is:

import { Injectable } from '@angular/core';

export class ServiceNameService {

  constructor() { }


A service has to have a few public methods.

Regular Expression: Any character that is NOT a letter or number

Have you tried str = str.replace(/\W|_/g,''); it will return a string without any character and you can specify if any especial character after the pipe bar | to catch them as well.

var str = "1324567890abc§$)% John Doe #$@'.replace(/\W|_/g, ''); it will return str = 1324567890abcJohnDoe

or look for digits and letters and replace them for empty string (""):

var str = "1324567890abc§$)% John Doe #$@".replace(/\w|_/g, ''); it will return str = '§$)% #$@';

How can I upload fresh code at github?

If you haven't already created the project in Github, do so on that site. If memory serves, they display a page that tells you exactly how to get your existing code into your new repository. At the risk of oversimplification, though, you'd follow Veeti's instructions, then:

git remote add [name to use for remote] [private URI] # associate your local repository to the remote
git push [name of remote] master # push your repository to the remote

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". in a Maven Project

The message you mention is quite clear:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See for further details.

SLF4J API could not find a binding, and decided to default to a NOP implementation. In your case slf4j-log4j12.jar was somehow not visible when the LoggerFactory class was loaded into memory, which is admittedly very strange. What does "mvn dependency:tree" tell you?

The various dependency declarations may not even be directly at cause here. I strongly suspect that a pre-1.6 version of slf4j-api.jar is being deployed without your knowledge.

How to get multiple selected values from select box in JSP?

Something along the lines of (using JSTL):

<p>Selected Values:
  <c:forEach items="${paramValues['select2']}" var="selectedValue">
    <li><c:out value="${selectedValue}" /></li>

read file in classpath


public class readFile {
     * feel free to make any modification I have have been here so I feel you
     * @param args
     * @throws InterruptedException
    public static void main(String[] args) throws InterruptedException {
        File dir = new File(".");// read file from same directory as source //
        if (dir.isDirectory()) {
            File[] files = dir.listFiles();
            for (File file : files) {
                // if you wanna read file name with txt files
                if (file.getName().contains("txt")) {

                // if you want to open text file and read each line then
                if (file.getName().contains("txt")) {
                    try {
                        // FileReader reads text files in the default encoding.
                        FileReader fileReader = new FileReader(
                        // Always wrap FileReader in BufferedReader.
                        BufferedReader bufferedReader = new BufferedReader(
                        String line;
                        // get file details and get info you need.
                        while ((line = bufferedReader.readLine()) != null) {
                            // here you can say...
                            // System.out.println(line.substring(0, 10)); this
                            // prints from 0 to 10 indext
                    } catch (FileNotFoundException ex) {
                        System.out.println("Unable to open file '"
                                + file.getName() + "'");
                    } catch (IOException ex) {
                        System.out.println("Error reading file '"
                                + file.getName() + "'");
                        // Or we could just do this:

    }`enter code here`


jquery animate background position

You cannot use simple jquery's Animate to do that as it involves 2 values.

To solve it just include Background Position Plugin and you can animate Backgrounds at will.

How to use DISTINCT and ORDER BY in same SELECT statement?

The problem is that the columns used in the ORDER BY aren't specified in the DISTINCT. To do this, you need to use an aggregate function to sort on, and use a GROUP BY to make the DISTINCT work.

Try something like this:

SELECT DISTINCT Category, MAX(CreationDate) 
FROM MonitoringJob 
GROUP BY Category 
ORDER BY MAX(CreationDate) DESC, Category

Taskkill /f doesn't kill a process

I had the exact same issue, found this fix on another site: powershell.exe "Get-Process processname| Stop-Process" it worked for me and I was in the same boat where I had to restart, the /T would not work.

Slidedown and slideup layout with animation

I use these easy functions, it work like jquery slideUp slideDown, use it in an helper class, just pass your view :

public static void expand(final View v) {
    v.measure(WindowManager.LayoutParams.MATCH_PARENT, WindowManager.LayoutParams.WRAP_CONTENT);
    final int targetHeight = v.getMeasuredHeight();

    // Older versions of android (pre API 21) cancel animations for views with a height of 0.
    v.getLayoutParams().height = 1;
    Animation a = new Animation()
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            v.getLayoutParams().height = interpolatedTime == 1
                    ? WindowManager.LayoutParams.WRAP_CONTENT
                    : (int)(targetHeight * interpolatedTime);

        public boolean willChangeBounds() {
            return true;

    // 1dp/ms
    a.setDuration((int) (targetHeight / v.getContext().getResources().getDisplayMetrics().density));

public static void collapse(final View v) {
    final int initialHeight = v.getMeasuredHeight();

    Animation a = new Animation()
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            if(interpolatedTime == 1){
                v.getLayoutParams().height = initialHeight - (int)(initialHeight * interpolatedTime);

        public boolean willChangeBounds() {
            return true;

    // 1dp/ms
    a.setDuration((int)(initialHeight / v.getContext().getResources().getDisplayMetrics().density));

TypeError: Missing 1 required positional argument: 'self'

You can also get this error by prematurely taking PyCharm's advice to annotate a method @staticmethod. Remove the annotation.

How to select an item from a dropdown list using Selenium WebDriver with java?

You can use 'Select' class of selenium WebDriver as posted by Maitreya. Sorry, but I'm a bit confused about, for selecting gender from drop down why to compare string with "Germany". Here is the code snippet,

Select gender = new Select(driver.findElement("gender")));

Import import; after adding the above code. Now gender will be selected which ever you gave ( Male/Female).

Why is visible="false" not working for a plain html table?

You probably are looking for style="display:none;" which will totally hide your element, whereas the visibility hides it but keeps the screen place it would take...

UPDATE: visible is not a valid property in HTML, that's why it didn't work... See my suggestion above to correctly hide your html element

How can I set size of a button?

Try with setPreferredSize instead of setSize.

UPDATE: GridLayout take up all space in its container, and BoxLayout seams to take up all the width in its container, so I added some glue-panels that are invisible and just take up space when the user stretches the window. I have just done this horizontally, and not vertically, but you could implement that in the same way if you want it.

Since GridLayout make all cells in the same size, it doesn't matter if they have a specified size. You have to specify a size for its container instead, as I have done.

import javax.swing.*;
import java.awt.*;

public class PanelModel {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Colored Trails");

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));

        JPanel firstPanel = new JPanel(new GridLayout(4, 4));
        firstPanel.setPreferredSize(new Dimension(4*100, 4*100));
        for (int i=1; i<=4; i++) {
            for (int j=1; j<=4; j++) {
                firstPanel.add(new JButton());

        JPanel firstGluePanel = new JPanel(new BorderLayout());
        firstGluePanel.add(firstPanel, BorderLayout.WEST);
        firstGluePanel.add(Box.createHorizontalGlue(), BorderLayout.CENTER);
        firstGluePanel.add(Box.createVerticalGlue(), BorderLayout.SOUTH);

        JPanel secondPanel = new JPanel(new GridLayout(13, 5));
        secondPanel.setPreferredSize(new Dimension(5*40, 13*40));
        for (int i=1; i<=5; i++) {
            for (int j=1; j<=13; j++) {
                secondPanel.add(new JButton());

        JPanel secondGluePanel = new JPanel(new BorderLayout());
        secondGluePanel.add(secondPanel, BorderLayout.WEST);
        secondGluePanel.add(Box.createHorizontalGlue(), BorderLayout.CENTER);
        secondGluePanel.add(Box.createVerticalGlue(), BorderLayout.SOUTH);



How to display Wordpress search results?

I am using searchform.php and search.php files as already mentioned, but here I provide the actual code.

Creating a Search Page codex page helps here and #Creating_a_Search_Page_Template shows the search query.

In my case I pass the $search_query arguments to the WP_Query Class (which can determine if is search query!). I then run The Loop to display the post information I want to, which in my case is the the_permalink and the_title.

Search box form:

<form class="search" method="get" action="<?php echo home_url(); ?>" role="search">
  <input type="search" class="search-field" placeholder="<?php echo esc_attr_x( 'Search …', 'placeholder' ) ?>" value="<?php echo get_search_query() ?>" name="s" title="<?php echo esc_attr_x( 'Search for:', 'label' ) ?>" />
  <button type="submit" role="button" class="btn btn-default right"/><span class="glyphicon glyphicon-search white"></span></button>

search.php template file:

    global $query_string;
    $query_args = explode("&", $query_string);
    $search_query = array();

    foreach($query_args as $key => $string) {
      $query_split = explode("=", $string);
      $search_query[$query_split[0]] = urldecode($query_split[1]);
    } // foreach

    $the_query = new WP_Query($search_query);
    if ( $the_query->have_posts() ) : 
    <!-- the loop -->

    <?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>
            <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
    <?php endwhile; ?>
    <!-- end of the loop -->

    <?php wp_reset_postdata(); ?>

<?php else : ?>
    <p><?php _e( 'Sorry, no posts matched your criteria.' ); ?></p>
<?php endif; ?>

How to read numbers separated by space using scanf

scanf uses any whitespace as a delimiter, so if you just say scanf("%d", &var) it will skip any whitespace and then read an integer (digits up to the next non-digit) and nothing more.

Note that whitespace is any whitespace -- spaces, tabs, newlines, or carriage returns. Any of those are whitespace and any one or more of them will serve to delimit successive integers.

mysql delete under safe mode

You can trick MySQL into thinking you are actually specifying a primary key column. This allows you to "override" safe mode.

Assuming you have a table with an auto-incrementing numeric primary key, you could do the following:


Disable Buttons in jQuery Mobile


Since this question still gets a lot of hits I'm also adding the current jQM Docs on how to disable the button:

Updated Examples:

enable enable a disabled form button


disable disable a form button


refresh update the form button
If you manipulate a form button via JavaScript, you must call the refresh method on it to update the visual styling.


Original Post Below:

Live Example:


Using @naugtur example below:


Link button example:


var clicked = false;

$('#myButton').click(function() {
    if(clicked === false) {
        clicked = true;
        alert('Button is now disabled');

$('#enableButton').click(function() {
    clicked = false; 


<div data-role="page" id="home">
    <div data-role="content">

        <a href="#" data-role="button" id="myButton">Click button</a>
        <a href="#" data-role="button" id="enableButton">Enable button</a>



Links styled like buttons have all the same visual options as true form-based buttons below, but there are a few important differences. Link-based buttons aren't part of the button plugin and only just use the underlying buttonMarkup plugin to generate the button styles so the form button methods (enable, disable, refresh) aren't supported. If you need to disable a link-based button (or any element), it's possible to apply the disabled class ui-disabled yourself with JavaScript to achieve the same effect.

How do I deal with installing peer dependencies in Angular CLI?

NPM package libraries have a section in the package.json file named peerDependencies. For example; a library built in Angular 8, will usually list Angular 8 as a dependency. This is a true dependency for anyone running less than version 8. But for anyone running version 8, 9 or 10, it's questionable whether any concern should be pursued.

I have been safely ignoring these messages on Angular Updates, but then again we do have Unit and Cypress Tests!

Getting the computer name in Java

I'm not so thrilled about the InetAddress.getLocalHost().getHostName() solution that you can find so many places on the Internet and indeed also here. That method will get you the hostname as seen from a network perspective. I can see two problems with this:

  1. What if the host has multiple network interfaces ? The host may be known on the network by multiple names. The one returned by said method is indeterminate afaik.

  2. What if the host is not connected to any network and has no network interfaces ?

All OS'es that I know of have the concept of naming a node/host irrespective of network. Sad that Java cannot return this in an easy way. This would be the environment variable COMPUTERNAME on all versions of Windows and the environment variable HOSTNAME on Unix/Linux/MacOS (or alternatively the output from host command hostname if the HOSTNAME environment variable is not available as is the case in old shells like Bourne and Korn).

I would write a method that would retrieve (depending on OS) those OS vars and only as a last resort use the InetAddress.getLocalHost().getHostName() method. But that's just me.

UPDATE (Unices)

As others have pointed out the HOSTNAME environment variable is typically not available to a Java application on Unix/Linux as it is not exported by default. Hence not a reliable method unless you are in control of the clients. This really sucks. Why isn't there a standard property with this information?

Alas, as far as I can see the only reliable way on Unix/Linux would be to make a JNI call to gethostname() or to use Runtime.exec() to capture the output from the hostname command. I don't particularly like any of these ideas but if anyone has a better idea I'm all ears. (update: I recently came across gethostname4j which seems to be the answer to my prayers).

Long read

I've created a long explanation in another answer on another post. In particular you may want to read it because it attempts to establish some terminology, gives concrete examples of when the InetAddress.getLocalHost().getHostName() solution will fail, and points to the only safe solution that I know of currently, namely gethostname4j.

It's sad that Java doesn't provide a method for obtaining the computername. Vote for JDK-8169296 if you are able to.

How can I append a string to an existing field in MySQL?

Update image field to add full URL, ignoring null fields:

UPDATE test SET image = CONCAT('',image) WHERE image IS NOT NULL;

Activating Anaconda Environment in VsCode

Unfortunately, this does not work on macOS. Despite the fact that I have export CONDA_DEFAULT_ENV='$HOME/anaconda3/envs/dev' in my .zshrc and "python.pythonPath": "${env.CONDA_DEFAULT_ENV}/bin/python", in my VSCode prefs, the built-in terminal does not use that environment's Python, even if I have started VSCode from the command line where that variable is set.

How to "git show" a merge commit with combined diff output even when every changed file agrees with one of the parents?

Look at the commit message:

commit 0e1329e551a5700614a2a34d8101e92fd9f2cad6 (HEAD, master)
Merge: fc17405 ee2de56
Author: Tilman Vogel <email@email>
Date:   Tue Feb 22 00:27:17 2011 +0100

Merge branch 'testing' into master

notice the line:

Merge: fc17405 ee2de56

take those two commit ids and reverse them. so in order get the diff that you want, you would do:

git diff ee2de56..fc17405

to show just the names of the changed files:

git diff --name-only ee2de56..fc17405

and to extract them, you can add this to your gitconfig:

exportfiles = !sh -c 'git diff $0 --name-only | "while read files; do mkdir -p \"$1/$(dirname $files)\"; cp -vf $files $1/$(dirname $files); done"'

then use it by doing:

git exportfiles ee2de56..fc17405 /c/temp/myproject

Using Javascript's atob to decode base64 doesn't properly decode utf-8 strings

Here is 2018 updated solution as described in the Mozilla Development Resources


function b64EncodeUnicode(str) {
    // first we use encodeURIComponent to get percent-encoded UTF-8,
    // then we convert the percent encodings into raw bytes which
    // can be fed into btoa.
    return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g,
        function toSolidBytes(match, p1) {
            return String.fromCharCode('0x' + p1);

b64EncodeUnicode('? à la mode'); // "4pyTIMOgIGxhIG1vZGU="
b64EncodeUnicode('\n'); // "Cg=="


function b64DecodeUnicode(str) {
    // Going backwards: from bytestream, to percent-encoding, to original string.
    return decodeURIComponent(atob(str).split('').map(function(c) {
        return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);

b64DecodeUnicode('4pyTIMOgIGxhIG1vZGU='); // "? à la mode"
b64DecodeUnicode('Cg=='); // "\n"

How much data / information can we save / store in a QR code?

See this table.

A 101x101 QR code, with high level error correction, can hold 3248 bits, or 406 bytes. Probably not enough for any meaningful SVG/XML data.

A 177x177 grid, depending on desired level of error correction, can store between 1273 and 2953 bytes. Maybe enough to store something small.

enter image description here

Getting a list item by index

you can use index to access list elements

List<string> list1 = new List<string>();
list1[0] //for getting the first element of the list

How to URL encode a string in Ruby

I was originally trying to escape special characters in a file name only, not on the path, from a full URL string.

ERB::Util.url_encode didn't work for my use:

helper.send(:url_encode, "\11\15")
# => ""

Based on two answers in "Why is URI.escape() marked as obsolete and where is this REGEXP::UNSAFE constant?", it looks like URI::RFC2396_Parser#escape is better than using URI::Escape#escape. However, they both are behaving the same to me:

# => """\11\15")
# => ""

svn cleanup: sqlite: database disk image is malformed

Do not waste your time on checking integrity or deleting data from work queue table because these are temporary solutions and it will hit you back after a while.

Just do another checkout and replace the existing .svn folder with the new one. Do an update and then it should go smooth.

Spring 3.0 - Unable to locate Spring NamespaceHandler for XML schema namespace []

A nice list of Maven Dependencies exists at : Spring Site The major artifacts needed are:

  1. spring-security-core
  2. Spring-security-web
  3. spring-security-config

Bootstrap 3 truncate long text inside rows of a table in a responsive way

I'm using bootstrap.
I used css parameters.

.table {

.table td {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;

and bootstrap grid system parameters, like this.

<th class="col-sm-2">Name</th>

<td class="col-sm-2">hoge</td>

Convert Map to JSON using Jackson

You should prefer Object Mapper instead. Here is the link for the same : Object Mapper - Spring MVC way of Obect to JSON

Two dimensional array in python

You can first append elements to the initialized array and then for convenience, you can convert it into a numpy array.

import numpy as np
a = [] # declare null array
a.append(['aa1']) # append elements
a_np = np.asarray(a) # convert to numpy array

Android sample bluetooth code to send a simple string via bluetooth

private OutputStream outputStream;
private InputStream inStream;

private void init() throws IOException {
    BluetoothAdapter blueAdapter = BluetoothAdapter.getDefaultAdapter();
    if (blueAdapter != null) {
        if (blueAdapter.isEnabled()) {
            Set<BluetoothDevice> bondedDevices = blueAdapter.getBondedDevices();

            if(bondedDevices.size() > 0) {
                Object[] devices = (Object []) bondedDevices.toArray();
                BluetoothDevice device = (BluetoothDevice) devices[position];
                ParcelUuid[] uuids = device.getUuids();
                BluetoothSocket socket = device.createRfcommSocketToServiceRecord(uuids[0].getUuid());
                outputStream = socket.getOutputStream();
                inStream = socket.getInputStream();

            Log.e("error", "No appropriate paired devices.");
        } else {
            Log.e("error", "Bluetooth is disabled.");

public void write(String s) throws IOException {

public void run() {
    final int BUFFER_SIZE = 1024;
    byte[] buffer = new byte[BUFFER_SIZE];
    int bytes = 0;
    int b = BUFFER_SIZE;

    while (true) {
        try {
            bytes =, bytes, BUFFER_SIZE - bytes);
        } catch (IOException e) {

Code coverage for Jest built on top of Jasmine

Jan 2019: Jest version 23.6

For anyone looking into this question recently especially if testing using npm or yarn directly

Currently, you don't have to change the configuration options

As per Jest official website, you can do the following to generate coverage reports:

1- For npm:

You must put -- before passing the --coverage argument of Jest

npm test -- --coverage

if you try invoking the --coverage directly without the -- it won't work

2- For yarn:

You can pass the --coverage argument of jest directly

yarn test --coverage

How to use relative/absolute paths in css URLs?

The URL is relative to the location of the CSS file, so this should work for you:


The relative URL goes two folders back, and then to the images folder - it should work for both cases, as long as the structure is the same.


Partial URLs are interpreted relative to the source of the style sheet, not relative to the document

Replace NA with 0 in a data frame column

Since nobody so far felt fit to point out why what you're trying doesn't work:

  1. NA == NA doesn't return TRUE, it returns NA (since comparing to undefined values should yield an undefined result).
  2. You're trying to call apply on an atomic vector. You can't use apply to loop over the elements in a column.
  3. Your subscripts are off - you're trying to give two indices into a$x, which is just the column (an atomic vector).

I'd fix up 3. to get to a$x[$x)] <- 0

Find JavaScript function definition in Chrome

Different browsers do this differently.

  1. First open console window by right clicking on the page and selecting "Inspect Element", or by hitting F12.

  2. In the console, type...

    • Firefox

    • Chrome


symfony 2 No route found for "GET /"

This work for me:

cache:clear --env=prod

How do I make a MySQL database run completely in memory?

In place of the Memory storage engine, one can consider MySQL Cluster. It is said to give similar performance but to support disk-backed operation for durability. I've not tried it, but it looks promising (and been in development for a number of years).

You can find the official MySQL Cluster documentation here.

What is the difference between min SDK version/target SDK version vs. compile SDK version?

The min sdk version is the minimum version of the Android operating system required to run your application.

The target sdk version is the version of Android that your app was created to run on.

The compile sdk version is the the version of Android that the build tools uses to compile and build the application in order to release, run, or debug.

Usually the compile sdk version and the target sdk version are the same.

How to execute the start script with Nodemon

To avoid a global install, add Nodemon as a dependency, then...


"scripts": {
    "start": "node ./bin/www",
    "start-dev": "./node_modules/nodemon/bin/nodemon.js ./bin/www"

How to set URL query params in Vue with Vue-Router

Here is the example in docs:

// with query, resulting in /register?plan=private
router.push({ path: 'register', query: { plan: 'private' }})


As mentioned in those docs, router.replace works like router.push

So, you seem to have it right in your sample code in question. But I think you may need to include either name or path parameter also, so that the router has some route to navigate to. Without a name or path, it does not look very meaningful.

This is my current understanding now:

  • query is optional for router - some additional info for the component to construct the view
  • name or path is mandatory - it decides what component to show in your <router-view>.

That might be the missing thing in your sample code.

EDIT: Additional details after comments

Have you tried using named routes in this case? You have dynamic routes, and it is easier to provide params and query separately:

routes: [
    { name: 'user-view', path: '/user/:id', component: UserView },
    // other routes

and then in your methods:

this.$router.replace({ name: "user-view", params: {id:"123"}, query: {q1: "q1"} })

Technically there is no difference between the above and this.$router.replace({path: "/user/123", query:{q1: "q1"}}), but it is easier to supply dynamic params on named routes than composing the route string. But in either cases, query params should be taken into account. In either case, I couldn't find anything wrong with the way query params are handled.

After you are inside the route, you can fetch your dynamic params as this.$ and your query params as this.$route.query.q1.

Table 'mysql.user' doesn't exist:ERROR

Your database may be corrupt. Try to check if mysql.user exists:

use mysql;
select * from user;

If these are missing you can try recreating the tables by using


or you may have to clean (completely remove it) and reinstall MySQL.

Jquery and HTML FormData returns "Uncaught TypeError: Illegal invocation"

Adding processData: false to the $.ajax options will fix this issue.

Drop data frame columns by name

Another possibility:

df <- df[, setdiff(names(df), c("a", "c"))]


df <- df[, grep('^(a|c)$', names(df), invert=TRUE)]

How to set focus to a button widget programmatically?

Try this:


Split string into string array of single characters

string input = "this is a test";
string[] afterSplit = input.Split();

foreach (var word in afterSplit)



How do I make a text input non-editable?

if you really want to use CSS, use following property which will make field non-editable.

pointer-events: none;

Iterating over arrays in Python 3

While iterating over a list or array with this method:

ar = [10, 11, 12]
for i in ar:
    theSum = theSum + ar[i]

You are actually getting the values of list or array sequentially in i variable. If you print the variable i inside the for loop. You will get following output:


However, in your code you are confusing i variable with index value of array. Therefore, while doing ar[i] will mean ar[10] for the first iteration. Which is of course index out of range throwing IndexError

Edit You can read this for better understanding of different methods of iterating over array or list in Python

Arrays.asList() of an array

I think you have found an example where auto-boxing doesn't really work. Because Arrays.asList(T... a) has a varargs parameter the compiler apparently considers the int[] and returns a List<int[]> with a single element in it.

You should change the method into this:

public int getTheNumber(Integer[] factors) {
    ArrayList<Integer> f = new ArrayList<Integer>(Arrays.asList(factors));  
    return f.get(0) * f.get(f.size() - 1);

and possibly add this for compatibility

public int getTheNumber(int[] factors) {
    Integer[] factorsInteger = new Integer[factors.length];
    for(int ii=0; ii<factors.length; ++ii) {
        factorsInteger[ii] = factors[ii];

    return getTheNumber(factorsInteger);

gulp command not found - error after installing gulp

  1. Install gulp globally.

    npm install -g gulp

  2. Install gulp locally in the project.

    npm install gulp

  3. Add below line in your package.json

    "scripts": { "gulp": "gulp" }

  4. Run gulp.

    npm run gulp

This worked for me.

Count distinct value pairs in multiple columns in SQL

You can also do something like:

SELECT COUNT(DISTINCT id + name + address) FROM mytable

Trying to embed newline in a variable in bash


  1. Inserting \n

    echo -e "${p}"
  2. Inserting a new line in the source code

    echo "${p}"
  3. Using $'\n' (only and )

    echo "${p}"


1. Inserting \n

echo -e "${p}"

echo -e interprets the two characters "\n" as a new line.

var="a b c"
for i in $var
   p="$p\n$i"            # Append
   unset first_loop
echo -e "$p"             # Use -e

Avoid extra leading newline

var="a b c"
for i in $var
   (( $first_loop )) &&  # "((...))" is bash specific
   p="$i"            ||  # First -> Set
   p="$p\n$i"            # After -> Append
   unset first_loop
echo -e "$p"             # Use -e

Using a function

   local p="$1"
   for i in "$@"
      p="$p\n$i"         # Append
   echo -e "$p"          # Use -e

var="a b c"
p=$( embed_newline $var )  # Do not use double quotes "$var"
echo "$p"

2. Inserting a new line in the source code

var="a b c"
for i in $var
$i"       # New line directly in the source code
echo "$p" # Double quotes required
          # But -e not required

Avoid extra leading newline

var="a b c"
for i in $var
   (( $first_loop )) &&  # "((...))" is bash specific
   p="$i"            ||  # First -> Set
$i"                      # After -> Append
   unset first_loop
echo "$p"                # No need -e

Using a function

   local p="$1"
   for i in "$@"
$i"                      # Append
   echo "$p"             # No need -e

var="a b c"
p=$( embed_newline $var )  # Do not use double quotes "$var"
echo "$p"

3. Using $'\n' (less portable)

and interprets $'\n' as a new line.

var="a b c"
for i in $var
echo "$p" # Double quotes required
          # But -e not required

Avoid extra leading newline

var="a b c"
for i in $var
   (( $first_loop )) &&  # "((...))" is bash specific
   p="$i"            ||  # First -> Set
   p="$p"$'\n'"$i"       # After -> Append
   unset first_loop
echo "$p"                # No need -e

Using a function

   local p="$1"
   for i in "$@"
      p="$p"$'\n'"$i"    # Append
   echo "$p"             # No need -e

var="a b c"
p=$( embed_newline $var )  # Do not use double quotes "$var"
echo "$p"

Output is the same for all


Special thanks to contributors of this answer: kevinf, Gordon Davisson, l0b0, Dolda2000 and tripleee.


How to pass a single object[] to a params object[]

new[] { (object) 0, (object) null, (object) false }

Creating a custom JButton in Java

I'm probably going a million miles in the wrong direct (but i'm only young :P ). but couldn't you add the graphic to a panel and then a mouselistener to the graphic object so that when the user on the graphic your action is preformed.

What's the difference between "Solutions Architect" and "Applications Architect"?

There are valid differences between types of architects:

Enterprise architects look at solutions for the enterprise aligining tightly with the enterprise strategy. Eg in a bank, they'll look at the complete IT landscape.

Solution architects focus on a particular solution, for example a new credit card acquiring system in a bank.

Domain architects focus on specific areas, for example an application architect or network architect.

Technical architects generally play the role of solution architects with less focus on the business aspect and more on the techology aspect.

Using Mockito with multiple calls to the same method with the same arguments

Following can be used as a common method to return different arguments on different method calls. Only thing we need to do is we need to pass an array with order in which objects should be retrieved in each call.

public static <Mock> Answer<Mock> getAnswerForSubsequentCalls(final Mock... mockArr) {
    return new Answer<Mock>() {
       private int count=0, size=mockArr.length;
       public Mock answer(InvocationOnMock invocation) throws throwable {
           Mock mock = null;
           for(; count<size && mock==null; count++){
                mock = mockArr[count];

           return mock;    

Ex. getAnswerForSubsequentCalls(mock1, mock3, mock2); will return mock1 object on first call, mock3 object on second call and mock2 object on third call. Should be used like when(something()).doAnswer(getAnswerForSubsequentCalls(mock1, mock3, mock2)); This is almost similar to when(something()).thenReturn(mock1, mock3, mock2);

Checking password match while typing

$(function() {
    $("#txtConfirmPassword").keyup(function() {
        var password = $("#txtNewPassword").val();
        $("#divCheckPasswordMatch").html(password == $(this).val()
            ? "Passwords match."
            : "Passwords do not match!"

Demo here

MySQL: Curdate() vs Now()

CURDATE() will give current date while NOW() will give full date time.

Run the queries, and you will find out whats the difference between them.

SELECT NOW();     -- You will get 2010-12-09 17:10:18
SELECT CURDATE(); -- You will get 2010-12-09

Scikit-learn: How to obtain True Positive, True Negative, False Positive and False Negative

The one liner to get true postives etc. out of the confusion matrix is to ravel it:

from sklearn.metrics import confusion_matrix

y_true = [1, 1, 0, 0]
y_pred = [1, 0, 1, 0]   

tn, fp, fn, tp = confusion_matrix(y_true, y_pred).ravel()
print(tn, fp, fn, tp)  # 1 1 1 1

How to scroll to the bottom of a RecyclerView? scrollToPosition doesn't work

If none of these worked,

you should try to use :

ConstraintLayout targetView = (ConstraintLayout) recyclerView.findViewHolderForAdapterPosition(adapter.getItemCount()-1).itemView;
targetView.getParent().requestChildFocus(targetView, targetView);

By doing this, you are requesting a certain ConstraintLayout (Or whatever you have) to be displayed. The scroll is instant.

I works even with keyboard shown.

Key error when selecting columns in pandas dataframe after read_csv

use sep='\s*,\s*' so that you will take care of spaces in column-names:

transactions = pd.read_csv('transactions.csv', sep=r'\s*,\s*',
                           header=0, encoding='ascii', engine='python')

alternatively you can make sure that you don't have unquoted spaces in your CSV file and use your command (unchanged)




['product_id', 'customer_id', 'store_id', 'promotion_id', 'month_of_year', 'quarter', 'the_year', 'store_sales', 'store_cost', 'unit_sales', 'fact_count']

css 100% width div not taking up full width of parent

html, body{ 

This tells the html to be 100% wide. But 100% refers to the whole browser window width, so no more than that.

You may want to set a min width instead.

html, body{ 

So it will be 100% as a minimum, bot more if needed.

Comparing two input values in a form validation with AngularJS

When upgrading angular to 1.3 and above I found an issue using Jacek Ciolek's great answer:

  • Add data to the reference field
  • Add the same data to the field with the directive on it (this field is now valid)
  • Go back to the reference field and change the data (directive field remains valid)

I tested rdukeshier's answer (updating var modelToMatch = element.attr('sameAs') to var modelToMatch = attrs.sameAs to retrieve the reference model correctly) but the same issue occurred.

To fix this (tested in angular 1.3 and 1.4) I adapted rdukeshier's code and added a watcher on the reference field to run all validations when the reference field is changed. The directive now looks like this:

angular.module('app', [])
  .directive('sameAs', function () {
    return {
      require: 'ngModel',
      link: function(scope, element, attrs, ctrl) {
        var modelToMatch = attrs.sameAs;      

        scope.$watch(attrs.sameAs, function() {

        ctrl.$validators.match = function(modelValue, viewValue) {
          return viewValue === scope.$eval(modelToMatch);

Updated codepen

Is it possible to get an Excel document's row count without loading the entire document into memory?

Adding on to what Hubro said, apparently get_highest_row() has been deprecated. Using the max_row and max_column properties returns the row and column count. For example:

    wb = load_workbook(path, use_iterators=True)
    sheet = wb.worksheets[0]

    row_count = sheet.max_row
    column_count = sheet.max_column

Simple way to change the position of UIView?

CGRectOffset has since been replaced with the instance method offsetBy.

For example, what used to be

aView.frame = CGRectOffset(aView.frame, 10, 10)

would now be

aView.frame = aView.frame.offsetBy(dx: CGFloat(10), dy: CGFloat(10))

How to mark a build unstable in Jenkins when running shell scripts

I thought I would post another answer for people that might be looking for something similar.

In our build job we have cases where we would want the build to continue, but be marked as unstable. For ours it's relating to version numbers.

So, I wanted to set a condition on the build and set the build to unstable if that condition is met.

I used the Conditional step (single) option as a build step.

Then I used Execute system Groovy script as the build step that would run when that condition is met.

I used Groovy Command and set the script the following

import hudson.model.*

def build = Thread.currentThread().executable
build.@result = hudson.model.Result.UNSTABLE


That seems to work quite well.

I stumbled upon the solution here

Can I create view with parameter in MySQL?

I previously came up with a different workaround that doesn't use stored procedures, but instead uses a parameter table and some connection_id() magic.

EDIT (Copied up from comments)

create a table that contains a column called connection_id (make it a bigint). Place columns in that table for parameters for the view. Put a primary key on the connection_id. replace into the parameter table and use CONNECTION_ID() to populate the connection_id value. In the view use a cross join to the parameter table and put WHERE param_table.connection_id = CONNECTION_ID(). This will cross join with only one row from the parameter table which is what you want. You can then use the other columns in the where clause for example where orders.order_id = param_table.order_id.

How to check if mod_rewrite is enabled in php?

I like Christian Roy's solution:

###  .htaccess

<IfModule mod_rewrite.c>

    # Tell PHP that the mod_rewrite module is ENABLED.

    RewriteEngine on
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    # The rest of your rewrite rules here


Then, you can check in your PHP code for

    array_key_exists('HTTP_MOD_REWRITE', $_SERVER);

No idea if this works also with IIS (I have no way to check) but the odds are good.

Merge 2 arrays of objects

Posting this because unlike the previous answers this one is generic, no external libraries, O(n), actually filters out the duplicate and keeps the order the OP is asking for (by placing the last matching element in place of first appearance):

function unique(array, keyfunc) {
    return array.reduce((result, entry) => {
        const key = keyfunc(entry)
        if(key in result.seen) {
            result.array[result.seen[key]] = entry
        } else {
            result.seen[key] = result.array.length
        return result
    }, { array: [], seen: {}}).array


var arr1 = new Array({name: "lang", value: "English"}, {name: "age", value: "18"})
var arr2 = new Array({name : "childs", value: '5'}, {name: "lang", value: "German"})

var arr3 = unique([...arr1, ...arr2], x =>
/* arr3 == [ 
    {name: "lang", value: "German"}, 
    {name: "age", value: "18"},
    {name: "childs", value: "5"}

Default optional parameter in Swift function

Optionals and default parameters are two different things.

An Optional is a variable that can be nil, that's it.

Default parameters use a default value when you omit that parameter, this default value is specified like this: func test(param: Int = 0)

If you specify a parameter that is an optional, you have to provide it, even if the value you want to pass is nil. If your function looks like this func test(param: Int?), you can't call it like this test(). Even though the parameter is optional, it doesn't have a default value.

You can also combine the two and have a parameter that takes an optional where nil is the default value, like this: func test(param: Int? = nil).

Find the number of downloads for a particular app in apple appstore

found a paper at: that suggests a formula to calculate the downloads:


How do I left align these Bootstrap form items?

"pull-left" is what you need, it looks like you are using Bootstrap 2, I am not sure if that is available, consider bootstrap 3, unless ofcourse it is a huge rework! ... for Bootstrap 3 but you need to make sure you have 12 columns in each row as well, otherwise you will have issues.

Why should I use core.autocrlf=true in Git?

For me.

Edit .gitattributes file.


*.dll binary

Then everything goes well.

htaccess redirect to https://www

Michals answer worked for me, albeit with one small modification:


when you have a single site security certificate, a browser that tries to access your page without https:// www. (or whichever domain your certificate covers) will display an ugly red warning screen before it even gets to receive the redirect to the safe and correct https page.


First use the redirect to the www (or whichever domain is covered by your certificate) and only then do the https redirect. This will ensure that your users are not confronted with any error because your browser sees a certificate that doesn't cover the current url.

#First rewrite any request to the wrong domain to use the correct one (here www.)
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

#Now, rewrite to HTTPS:
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Python Requests throwing SSLError

I had to upgrade from Python 3.4.0 to 3.4.6

pyenv virtualenv 3.4.6 myvenv
pyenv activate myvenv
pip install -r requirements.txt

Sending mail from Python using SMTP


import smtplib
from email.message import EmailMessage
from getpass import getpass

password = getpass()

message = EmailMessage()
message.set_content('Message content here')
message['Subject'] = 'Your subject here'
message['From'] = "USERNAME@DOMAIN"
message['To'] = "[email protected]"

    smtp_server = None
    smtp_server = smtplib.SMTP("YOUR.MAIL.SERVER", 587)
    smtp_server.login("USERNAME@DOMAIN", password)
except Exception as e:
    print("Error: ", str(e))
    if smtp_server is not None:

If you want to use Port 465 you have to create an SMTP_SSL object.

How to change heatmap.2 color range in R?

I got the color range to be asymmetric simply by changing the symkey argument to FALSE

symm=F,symkey=F,symbreaks=T, scale="none"

Solved the color issue with colorRampPalette with the breaks argument to specify the range of each color, e.g.

colors = c(seq(-3,-2,length=100),seq(-2,0.5,length=100),seq(0.5,6,length=100))

my_palette <- colorRampPalette(c("red", "black", "green"))(n = 299)


heatmap.2(as.matrix(SeqCountTable), col=my_palette, 
    breaks=colors,"none", trace="none", 
        dendrogram=c("row"), symm=F,symkey=F,symbreaks=T, scale="none")

How can I see the request headers made by curl when sending a request to the server?

You can see it by using -iv

$> curl  -ivH "apikey:ad9ff3d36888957" --form  "file=@/home/mar/workspace/images/8.jpg" --form "language=eng" --form "isOverlayRequired=true"

java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader

-if not available then first add that file and add android.useDeprecatedNdk=true

-use this code in build.gradle

defaultConfig {
    applicationId 'com.example.application'
    minSdkVersion 16
    targetSdkVersion 21
    versionCode 11
    versionName "1.1"
    ndk {
        abiFilters "armeabi"


Vertical divider CSS

.headerDivider {
     border-left:1px solid #38546d; 
     border-right:1px solid #16222c; 

<div class="headerDivider"></div>

How to add a Hint in spinner in XML

It is very simple if position is '0' then call onNothingSelected method in OnItemSelectedListener. It worked fine for me.

      spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

            **if (position == 0)
            else {

                String mechanicType = mechanicTpes[position];
                Toast.makeText(FirstUser.this, "Mechanic Tpye : "+mechanicType, Toast.LENGTH_SHORT).show();


        public void onNothingSelected(AdapterView<?> parent) {
            Toast.makeText(FirstUser.this, "NOTHING SELECTED IN SPINNER", Toast.LENGTH_SHORT).show();


Running command line silently with VbScript and getting output?

You can redirect output to a file and then read the file:

return = WshShell.Run("cmd /c C:\snmpset -c ... > c:\temp\output.txt", 0, true)

Set fso  = CreateObject("Scripting.FileSystemObject")
Set file = fso.OpenTextFile("c:\temp\output.txt", 1)
text = file.ReadAll

Insert images to XML file

XML is not a format for storing images, neither binary data. I think it all depends on how you want to use those images. If you are in a web application and would want to read them from there and display them, I would store the URLs. If you need to send them to another web endpoint, I would serialize them, rather than persisting manually in XML. Please explain what is the scenario.

PostgreSQL delete with inner join

If you have more than one join you could use comma separated USING statements:

      AAA AS a 
      BBB AS b,
      CCC AS c
  AND =
  AND a.uid = 12345 
  AND c.gid = 's434sd4'


CSS3's border-radius property and border-collapse:collapse don't mix. How can I use border-radius to create a collapsed table with rounded corners?

I started experiment with "display" and I found that: border-radius, border, margin, padding, in a table are displayed with:

display: inline-table;

For example

table tbody tr {
  display: inline-table;
  width: 960px; 
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;

But we need set a width of every column

tr td.first-column {
  width: 100px;
tr td.second-column {
  width: 860px;

Bulk Record Update with SQL

Your way is correct, and here is another way you can do it:

update      Table1
set         Description = t2.Description
from        Table1 t1
inner join  Table2 t2
on          t1.DescriptionID = t2.ID

The nested select is the long way of just doing a join.

Jquery Ajax Loading image

Try something like this:

<div id="LoadingImage" style="display: none">
  <img src="" />

  function ajaxCall(){
        type: "GET", 
        url: surl, 
        dataType: "jsonp", 
        cache : false, 
        jsonp : "onJSONPLoad", 
        jsonpCallback: "newarticlescallback", 
        crossDomain: "true", 
        success: function(response) { 
        error: function (xhr, status) {  
          alert('Unknown error ' + status); 

A default document is not configured for the requested URL, and directory browsing is not enabled on the server

In my case, I had to install the Microsoft.Owin.Host.SystemWeb package.

I was getting the same message as you did, but then noticed I couldn't even hit a breakpoint in Startup.cs which then let me to this SO thread.

React Hook Warnings for async function in useEffect: useEffect function must return a cleanup function or nothing

I suggest to look at Dan Abramov (one of the React core maintainers) answer here:

I think you're making it more complicated than it needs to be.

function Example() {
  const [data, dataSet] = useState<any>(null)

  useEffect(() => {
    async function fetchMyAPI() {
      let response = await fetch('api/data')
      response = await response.json()

  }, [])

  return <div>{JSON.stringify(data)}</div>

Longer term we'll discourage this pattern because it encourages race conditions. Such as — anything could happen between your call starts and ends, and you could have gotten new props. Instead, we'll recommend Suspense for data fetching which will look more like

const response =;

and no effects. But in the meantime you can move the async stuff to a separate function and call it.

You can read more about experimental suspense here.

If you want to use functions outside with eslint.

 function OutsideUsageExample() {
  const [data, dataSet] = useState<any>(null)

  const fetchMyAPI = useCallback(async () => {
    let response = await fetch('api/data')
    response = await response.json()
  }, [])

  useEffect(() => {
  }, [fetchMyAPI])

  return (
      <div>data: {JSON.stringify(data)}</div>
        <button onClick={fetchMyAPI}>manual fetch</button>

If you will use useCallback, look at example of how it works useCallback. Sandbox.

import React, { useState, useEffect, useCallback } from "react";

export default function App() {
  const [counter, setCounter] = useState(1);

  // if counter is changed, than fn will be updated with new counter value
  const fn = useCallback(() => {
    setCounter(counter + 1);
  }, [counter]);

  // if counter is changed, than fn will not be updated and counter will be always 1 inside fn
  /*const fnBad = useCallback(() => {
      setCounter(counter + 1);
    }, []);*/

  // if fn or counter is changed, than useEffect will rerun
  useEffect(() => {
    if (!(counter % 2)) return; // this will stop the loop if counter is not even

  }, [fn, counter]);

  // this will be infinite loop because fn is always changing with new counter value
  /*useEffect(() => {
  }, [fn]);*/

  return (
      <div>Counter is {counter}</div>
      <button onClick={fn}>add +1 count</button>

How do I get the name of the active user via the command line in OS X?

I'm pretty sure the terminal in OS X is just like unix, so the command would be:


I don't have a mac on me at the moment so someone correct me if I'm wrong.

NOTE - The whoami utility has been obsoleted, and is equivalent to id -un. It will give you the current user

Create File If File Does Not Exist

This will enable appending to file using StreamWriter

 using (StreamWriter stream = new StreamWriter("YourFilePath", true)) {...}

This is default mode, not append to file and create a new file.

using (StreamWriter stream = new StreamWriter("YourFilePath", false)){...}
using (StreamWriter stream = new StreamWriter("YourFilePath")){...}

Anyhow if you want to check if the file exists and then do other things,you can use

using (StreamWriter sw = (File.Exists(path)) ? File.AppendText(path) : File.CreateText(path))

git push rejected: error: failed to push some refs

for me following worked, just ran these command one by one

git pull -r origin master

git push -f origin your_branch

MD5 is 128 bits but why is it 32 characters?

MD5 yields hexadecimal digits (0-15 / 0-F), so they are four bits each. 128 / 4 = 32 characters.

SHA-1 yields hexadecimal digits too (0-15 / 0-F), so 160 / 4 = 40 characters.

(Since they're mathematical operations, most hashing functions' output is commonly represented as hex digits.)

You were probably thinking of ASCII text characters, which are 8 bits.

git command to move a folder inside another

Make sure you have added all your changes to the staging area before running

git mv oldFolderName newFoldername

git fails with error

fatal: bad source, source=oldFolderName/somepath/, destination=newFolderName/somepath/

if there are any unadded files, so I just found out.

Java program to connect to Sql Server and running the sample query From Eclipse

Refer the below link.

There are two important changes that you should make

driver name as ""

& in URL "jdbc:sqlserver://localhost:1433"+";databaseName=AdventureWorks2008R2"

Why is vertical-align:text-top; not working in CSS

The problem I had can't be made out from the info I have provided:

  • I had the text enclosed in old school <p> tags.

I changed the <p> to <span> and it works fine.

Python equivalent for HashMap

You need a dict:

my_dict = {'cheese': 'cake'}

Example code (from the docs):

>>> a = dict(one=1, two=2, three=3)
>>> b = {'one': 1, 'two': 2, 'three': 3}
>>> c = dict(zip(['one', 'two', 'three'], [1, 2, 3]))
>>> d = dict([('two', 2), ('one', 1), ('three', 3)])
>>> e = dict({'three': 3, 'one': 1, 'two': 2})
>>> a == b == c == d == e

You can read more about dictionaries here.

Combining paste() and expression() functions in plot labels

If x^2 and y^2 were expressions already given in the variable squared, this solves the problem:

labNames <- c('xLab','yLab')
squared <- c(expression('x'^2), expression('y'^2))

xlab <- eval(bquote(expression(.(labNames[1]) ~ .(squared[1][[1]]))))
ylab <- eval(bquote(expression(.(labNames[2]) ~ .(squared[2][[1]]))))

plot(c(1:10), xlab = xlab, ylab = ylab)

Please note the [[1]] behind squared[1]. It gives you the content of "expression(...)" between the brackets without any escape characters.

EXCEL VBA, inserting blank row and shifting cells

Sub Addrisk()

Dim rActive As Range
Dim Count_Id_Column as long

Set rActive = ActiveCell

Application.ScreenUpdating = False

with thisworkbook.sheets(1) 'change to "sheetname" or sheetindex
    for i = 1 to .range("A1045783").end(xlup).row
        if 'something'  = 'something' then
            .range("A" & i).EntireRow.Copy 'add thisworkbook.sheets(index_of_sheet) if you copy from another sheet
            .range("A" & i).entirerow.insert shift:= xldown 'insert and shift down, can also use xlup
            .range("A" & i + 1).EntireRow.paste 'paste is all, all other defs are less.
            'change I to move on to next row (will get + 1 end of iteration)
            i = i + 1
        end if

            On Error Resume Next
            On Error GoTo 0

        End With
    next i
End With

Application.CutCopyMode = False
Application.ScreenUpdating = True 're-enable screen updates

End Sub

Adding author name in Eclipse automatically to existing files

To old files I don't know how to do it... I think you will need a script to go thru all files and add the header.

To change the new ones you can do this.

Go to Eclipse menu bar

  1. Window menu.
  2. Preferences
  3. search for Templates
  4. go to Code templates
  5. click on +code
  6. Click on New Java files
  7. Click Edit
  8. add


And it's done every new File will have your name on it !

Mocking python function based on input arguments

As indicated at Python Mock object with method called multiple times

A solution is to write my own side_effect

def my_side_effect(*args, **kwargs):
    if args[0] == 42:
        return "Called with 42"
    elif args[0] == 43:
        return "Called with 43"
    elif kwargs['foo'] == 7:
        return "Foo is seven"

mockobj.mockmethod.side_effect = my_side_effect

That does the trick

How to create multiple page app using react

(Make sure to install react-router using npm!)

To use react-router, you do the following:

  1. Create a file with routes defined using Route, IndexRoute components

  2. Inject the Router (with 'r'!) component as the top-level component for your app, passing the routes defined in the routes file and a type of history (hashHistory, browserHistory)

  3. Add {this.props.children} to make sure new pages will be rendered there
  4. Use the Link component to change pages

Step 1 routes.js

import React from 'react';
import { Route, IndexRoute } from 'react-router';

 * Import all page components here
import App from './components/App';
import MainPage from './components/MainPage';
import SomePage from './components/SomePage';
import SomeOtherPage from './components/SomeOtherPage';

 * All routes go here.
 * Don't forget to import the components above after adding new route.
export default (
  <Route path="/" component={App}>
    <IndexRoute component={MainPage} />
    <Route path="/some/where" component={SomePage} />
    <Route path="/some/otherpage" component={SomeOtherPage} />

Step 2 entry point (where you do your DOM injection)

// You can choose your kind of history here (e.g. browserHistory)
import { Router, hashHistory as history } from 'react-router';
// Your routes.js file
import routes from './routes';

  <Router routes={routes} history={history} />,

Step 3 The App component (props.children)

In the render for your App component, add {this.props.children}:

render() {
  return (
        This is my website!


        Your copyright message

Step 4 Use Link for navigation

Anywhere in your component render function's return JSX value, use the Link component:

import { Link } from 'react-router';
<Link to="/some/where">Click me</Link>

Extract data from XML Clob using SQL from Oracle Database


SELECT EXTRACTVALUE(xmltype(testclob), '/DCResponse/ContextData/Field[@key="Decision"]') 
FROM traptabclob;

Here is a sqlfiddle demo

How to fix Python indentation

Try Emacs. It has good support for indentation needed in Python. Please check this link

JFrame.dispose() vs System.exit()

  • If you have multiple windows open and only want to close the one that was closed use JFrame.dispose().

  • If you want to close all windows and terminate the application use System.exit()

Creating email templates with Django

I have made django-templated-email in an effort to solve this problem, inspired by this solution (and the need to, at some point, switch from using django templates to using a mailchimp etc. set of templates for transactional, templated emails for my own project). It is still a work-in-progress though, but for the example above, you would do:

from templated_email import send_templated_mail
        '[email protected]',
        ['[email protected]'],
        { 'username':username }

With the addition of the following to (to complete the example):


This will automatically look for templates named 'templated_email/email.txt' and 'templated_email/email.html' for the plain and html parts respectively, in the normal django template dirs/loaders (complaining if it cannot find at least one of those).

How can I import Swift code to Objective-C?

Go to build settings in your project file and search for "Objective-C Generated Interface Header Name. The value of that property is the name that you should include.

If your "Product Module Name" property (the one that the above property depends on by default) varies depending on whether you compile for test/debug/release/etc (like it does in my case), then make this property independent of that variation by setting a custom name.

Vim: faster way to select blocks of text in visual mode

Shift+V n j or Shift+V n k

This selects the current line and the next/previous n lines. I find it very useful.

Calling a javascript function in another js file

use "var" while creating function, then you can access that from another file. make sure both files are well connected to your project and can access each other.


var firstLetterUppercase = function(str) {
   str = str.toLowerCase().replace(/\b[a-z]/g, function(letter) {
      return letter.toUpperCase();
   return str;

accessing this function/variable form file_2.js file


output => Gobinda

hope this will help somebody, happy coding !!!

SQL Server "AFTER INSERT" trigger doesn't see the just-inserted row

Is it possible the INSERT is valid, but that a separate UPDATE is done afterwards that is invalid but wouldn't fire the trigger?

Beginner Python: AttributeError: 'list' object has no attribute

You need to pass the values of the dict into the Bike constructor before using like that. Or, see the namedtuple -- seems more in line with what you're trying to do.

If two cells match, return value from third

I think what you want is something like:


I should mention that MATCH checks the position at which the value can be found within A:A (given the 0, or FALSE, parameter, it looks only for an exact match and given its nature, only the first instance found) then INDEX returns the value at that position within B:B.

Change link color of the current page with CSS

include this! on your page where you want to change the colors save as .php

<?php include("includes/navbar.php"); ?>

then add a new file in an includes folder.


<div <?php //Using REQUEST_URI

$currentpage = $_SERVER['REQUEST_URI'];

if(preg_match("/index/i", $currentpage)||($currentpage=="/"))
    echo " class=\"navbarorange/*the css class for your nav div*/\" ";
elseif(preg_match("/about/*or second page name*//i", $currentpage))
    echo " class=\"navbarpink\" ";
elseif(preg_match("/contact/* or edit 3rd page name*//i", $currentpage))
    echo " class=\"navbargreen\" ";?> >

wamp server does not start: Windows 7, 64Bit

My solution to fix that problem was the following:

Start > search > cmd.exe (Run as administrator)

Inside the Command Prompt (cmd.exe) type:

cd c:/wamp/bin/apache/ApacheX.X.X/bin
httpd.exe -e debug

**Note that the ApacheX.X.X is the version of the Apache wamp is running.

This should output what the apache server is doing. The error that causes Apache from loading should be in there. My problem was that httpd.conf was trying to load a DLL that was missing or was corrupted (php5apache2_4.dll). As soon as I overwrote this file, I restarted Wamp and everything ran smooth.

LIMIT 10..20 in SQL Server

Unfortunately, the ROW_NUMBER() is the best you can do. It's actually more correct, because the results of a limit or top clause don't really have meaning without respect to some specific order. But it's still a pain to do.

Update: Sql Server 2012 adds a limit -like feature via OFFSET and FETCH keywords. This is the ansi-standard approach, as opposed to LIMIT, which is a non-standard MySql extension.

How to make a variadic macro (variable number of arguments)

#define DEBUG

#ifdef DEBUG
  #define PRINT print
  #define PRINT(...) ((void)0) //strip out PRINT instructions from code

void print(const char *fmt, ...) {

    va_list args;
    va_start(args, fmt);
    vsprintf(str, fmt, args);

        printf("%s\n", str);


int main() {
   PRINT("[%s %d, %d] Hello World", "March", 26, 2009);
   return 0;

If the compiler does not understand variadic macros, you can also strip out PRINT with either of the following:

#define PRINT //


#define PRINT if(0)print

The first comments out the PRINT instructions, the second prevents PRINT instruction because of a NULL if condition. If optimization is set, the compiler should strip out never executed instructions like: if(0) print("hello world"); or ((void)0);

changing iframe source with jquery

Should work.

Here's a working example:


function loadIframe(iframeName, url) {
    var $iframe = $('#' + iframeName);
    if ($iframe.length) {
        return false;
    return true;

Appending a line break to an output file in a shell script

I'm betting the problem is that Cygwin is writing Unix line endings (LF) to the file, and you're opening it with a program that expects Windows line-endings (CRLF). To determine if this is the case — and for a bit of a hackish workaround — try:

echo "`date` User `whoami` started the script."$'\r' >> output.log

(where the $'\r' at the end is an extra carriage-return; it, plus the Unix line ending, will result in a Windows line ending).

Reading InputStream as UTF-8

Solved my own problem. This line:

BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));

needs to be:

BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));

or since Java 7:

BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream(), StandardCharsets.UTF_8));

git with development, staging and production branches

Actually what made this so confusing is that the Beanstalk people stand behind their very non-standard use of Staging (it comes before development in their diagram, and it's not a mistake!

How to convert an XML file to nice pandas dataframe?

You can easily use xml (from the Python standard library) to convert to a pandas.DataFrame. Here's what I would do (when reading from a file replace xml_data with the name of your file or file object):

import pandas as pd
import xml.etree.ElementTree as ET
import io

def iter_docs(author):
    author_attr = author.attrib
    for doc in author.iter('document'):
        doc_dict = author_attr.copy()
        doc_dict['data'] = doc.text
        yield doc_dict

xml_data = io.StringIO(u'''\
<author type="XXX" language="EN" gender="xx" feature="xx" web="">
    <documents count="N">
        <document KEY="e95a9a6c790ecb95e46cf15bee517651" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="bc360cfbafc39970587547215162f0db" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="19e71144c50a8b9160b3f0955e906fce" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="21d4af9021a174f61b884606c74d9e42" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="28a45eb2460899763d709ca00ddbb665" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="a0c0712a6a351f85d9f5757e9fff8946" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="626726ba8d34d15d02b6d043c55fe691" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...]
        <document KEY="2cb473e0f102e2e4a40aa3006e412ae4" web=""><![CDATA[A large text with lots of strings and punctuations symbols [...] [...]

etree = ET.parse(xml_data) #create an ElementTree object 
doc_df = pd.DataFrame(list(iter_docs(etree.getroot())))

If there are multiple authors in your original document or the root of your XML is not an author, then I would add the following generator:

def iter_author(etree):
    for author in etree.iter('author'):
        for row in iter_docs(author):
            yield row

and change doc_df = pd.DataFrame(list(iter_docs(etree.getroot()))) to doc_df = pd.DataFrame(list(iter_author(etree)))

Have a look at the ElementTree tutorial provided in the xml library documentation.

How do you auto format code in Visual Studio?

Visual Studio Extension - CodeMaid is pretty fine.

WPF Timer Like C# Timer

With Dispatcher you will need to include

using System.Windows.Threading;

Also note that if you right-click DispatcherTimer and click Resolve it should add the appropriate references.

Angular - Can't make ng-repeat orderBy work

Here's a version of @Julian Mosquera's code that also supports sorting by object key:

yourApp.filter('orderObjectBy', function () {
    return function (items, field, reverse) {
        // Build array
        var filtered = [];
        for (var key in items) {
            if (field === 'key')
        // Sort array
        filtered.sort(function (a, b) {
            if (field === 'key')
                return (a > b ? 1 : -1);
                return (a[field] > b[field] ? 1 : -1);
        // Reverse array
        if (reverse)
        return filtered;

Why is json_encode adding backslashes?

I just came across this issue in some of my scripts too, and it seemed to be happening because I was applying json_encode to an array wrapped inside another array which was also json encoded. It's easy to do if you have multiple foreach loops in a script that creates the data. Always apply json_encode at the end.

Here is what was happening. If you do:

$data[] = json_encode(['test' => 'one', 'test' => '2']);
$data[] = json_encode(['test' => 'two', 'test' => 'four']);
echo json_encode($data);

The result is:


So, what you actually need to do is:

$data[] = ['test' => 'one', 'test' => '2'];
$data[] = ['test' => 'two', 'test' => 'four'];
echo json_encode($data);

And this will return


How to force Sequential Javascript Execution?

I am an old hand at programming and came back recently to my old passion and am struggling to fit in this Object oriented, event driven bright new world and while i see the advantages of the non sequential behavior of Javascript there are time where it really get in the way of simplicity and reusability. A simple example I have worked on was to take a photo (Mobile phone programmed in javascript, HTML, phonegap, ...), resize it and upload it on a web site. The ideal sequence is :

  1. Take a photo
  2. Load the photo in an img element
  3. Resize the picture (Using Pixastic)
  4. Upload it to a web site
  5. Inform the user on success failure

All this would be a very simple sequential program if we would have each step returning control to the next one when it is finished, but in reality :

  1. Take a photo is async, so the program attempt to load it in the img element before it exist
  2. Load the photo is async so the resize picture start before the img is fully loaded
  3. Resize is async so Upload to the web site start before the Picture is completely resized
  4. Upload to the web site is asyn so the program continue before the photo is completely uploaded.

And btw 4 of the 5 steps involve callback functions.

My solution thus is to nest each step in the previous one and use .onload and other similar stratagems, It look something like this :

takeAPhoto(takeaphotocallback(photo) {
  photo.onload = function () {
    resizePhoto(photo, resizePhotoCallback(photo) {
      uploadPhoto(photo, uploadPhotoCallback(status) {

(I hope I did not make too many mistakes bringing the code to it's essential the real thing is just too distracting)

This is I believe a perfect example where async is no good and sync is good, because contrary to Ui event handling we must have each step finish before the next is executed, but the code is a Russian doll construction, it is confusing and unreadable, the code reusability is difficult to achieve because of all the nesting it is simply difficult to bring to the inner function all the parameters needed without passing them to each container in turn or using evil global variables, and I would have loved that the result of all this code would give me a return code, but the first container will be finished well before the return code will be available.

Now to go back to Tom initial question, what would be the smart, easy to read, easy to reuse solution to what would have been a very simple program 15 years ago using let say C and a dumb electronic board ?

The requirement is in fact so simple that I have the impression that I must be missing a fundamental understanding of Javsascript and modern programming, Surely technology is meant to fuel productivity right ?.

Thanks for your patience

Raymond the Dinosaur ;-)

Can I specify multiple users for myself in .gitconfig?

Since git 2.13, it is possible to solve this using newly introduced Conditional includes.

An example:

Global config ~/.gitconfig

    name = John Doe
    email = [email protected]

[includeIf "gitdir:~/work/"]
    path = ~/work/.gitconfig

Work specific config ~/work/.gitconfig

    email = [email protected]

good postgresql client for windows?

Actually there is a freeware version of EMS's SQL Manager which is quite powerful

Add a new line to the end of a JtextArea

Are you using JTextArea's append(String) method to add additional text?

JTextArea txtArea = new JTextArea("Hello, World\n", 20, 20);
txtArea.append("Goodbye Cruel World\n");

"SDK Platform Tools component is missing!"

Installing Android SDKs is done via the "Android SDK and AVD Manager"... there's a shortcut on Eclipse's "Window" menu, or you can run the .exe from the root of your existing Android SDK installation.

Yes I think installing the 2.3 SDK will fix your problem... you can install older SDKs at the same time. The important thing is that the structure of the SDK changed in 2.3 with some tools (such as ADB) moving from sdkroot\tools to sdkroot\platform-tools. Quite possibly the very latest ADT plugin isn't massively backwards-compatible re that change.

How to set JAVA_HOME path on Ubuntu?

add JAVA_HOME to the file:


for it to be available to the entire system (you would need to restart Ubuntu though)

Bash mkdir and subfolders


Poor mans security folder (to protect a public shared folder from little prying eyes ;) )

mkdir -p {0..9}/{0..9}/{0..9}/{0..9}

Now you can put your files in a pin numbered folder. Not exactly waterproof, but it's a barrier for the youngest.

Getting list of tables, and fields in each, in a database


SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS for get all table name. Try it on sqlserver,

Detect if page has finished loading

jQuery(window).load(function () {
    alert('page is loaded');

    setTimeout(function () {
        alert('page is loaded and 1 minute has passed');   
    }, 60000);



See also for an explanation on the jQuery(window).load.


A detailed explanation on how javascript loading works and the two events DOMContentLoaded and OnLoad can be found on this page.

DOMContentLoaded: When the DOM is ready to be manipulated. jQuery's way of capturing this event is with jQuery(document).ready(function () {});.

OnLoad: When the DOM is ready and all assets - this includes images, iframe, fonts, etc - have been loaded and the spinning wheel / hour class disappear. jQuery's way of capturing this event is the above mentioned jQuery(window).load.

How to sort a dataframe by multiple column(s)

if SQL comes naturally to you, sqldf package handles ORDER BY as Codd intended.

How to draw a graph in PHP?

Have no idea about gd2, but I have done a similar thing with gd and it was not that hard.

Go to and search for things like

  • ImageCreate
  • imageline
  • imagestring

It's not as flashy as some of those other solution out there, but since you generate a picture it will work in all browsers. (except lynx... :-) )


Update: I nearly forgot, don't use jpeg for this type of pictures. The jpeg artefacts will be really annoying, png is a better solution.

Codeigniter unset session

I use the old PHP way..It unsets all session variables and doesn't require to specify each one of them in an array. And after unsetting the variables we destroy the session.


How to set up file permissions for Laravel?

Add to composer.json

"scripts": {
    "post-install-cmd": [
      "chgrp -R www-data storage bootstrap/cache",
      "chmod -R ug+rwx storage bootstrap/cache"

After composer install

SQL variable to hold list of integers

Table variable

declare @listOfIDs table (id int);
insert @listOfIDs(id) values(1),(2),(3);    

select *
from TabA
where TabA.ID in (select id from @listOfIDs)


declare @listOfIDs varchar(1000);
SET @listOfIDs = ',1,2,3,'; --in this solution need put coma on begin and end

select *
from TabA
where charindex(',' + CAST(TabA.ID as nvarchar(20)) + ',', @listOfIDs) > 0

Why isn't my Pandas 'apply' function referencing multiple columns working?

All of the suggestions above work, but if you want your computations to by more efficient, you should take advantage of numpy vector operations (as pointed out here).

import pandas as pd
import numpy as np

df = pd.DataFrame ({'a' : np.random.randn(6),
             'b' : ['foo', 'bar'] * 3,
             'c' : np.random.randn(6)})

Example 1: looping with pandas.apply():

def my_test2(row):
    return row['a'] % row['c']

df['Value'] = df.apply(my_test2, axis=1)

The slowest run took 7.49 times longer than the fastest. This could mean that an intermediate result is being cached. 1000 loops, best of 3: 481 µs per loop

Example 2: vectorize using pandas.apply():

df['a'] % df['c']

The slowest run took 458.85 times longer than the fastest. This could mean that an intermediate result is being cached. 10000 loops, best of 3: 70.9 µs per loop

Example 3: vectorize using numpy arrays:

df['a'].values % df['c'].values

The slowest run took 7.98 times longer than the fastest. This could mean that an intermediate result is being cached. 100000 loops, best of 3: 6.39 µs per loop

So vectorizing using numpy arrays improved the speed by almost two orders of magnitude.

How to add a new line in textarea element?

To get a new line inside text-area, put an actual line-break there:

    <textarea cols='60' rows='8'>This is my statement one._x000D_
    This is my statement2</textarea>

Python wildcard search in string

Why don't you just use the join function? In a regex findall() or group() you will need a string so:

import re
regex = re.compile('th.s')
l = ['this', 'is', 'just', 'a', 'test']
matches = re.findall(regex, ' '.join(l)) #Syntax option 1
matches = regex.findall(' '.join(l)) #Syntax option 2

The join() function allows you to transform a list in a string. The single quote before join is what you will put in the middle of each string on list. When you execute this code part (' '.join(l)) you'll receive this:

'this is just a test'

So you can use the findal() function.

I know i am 7 years late, but i recently create an account because I'm studying and other people could have the same question. I hope this help you and others.

Update After @FélixBrunet comments:

import re
regex = re.compile(r'th.s')
l = ['this', 'is', 'just', 'a', 'test','th','s', 'this is']

matches2=[] #declare a list
for i in range(len(l)): #loop with the iterations = list l lenght. This avoid the first item commented by @Felix
if regex.findall(l[i]) != []: #if the position i is not an empty list do the next line. PS: remember regex.findall() command return a list.
    if l[i]== ''.join(regex.findall(l[i])): # If the string of i position of l list = command findall() i position so it'll allow the program do the next line - this avoid the second item commented by @Félix
        matches2.append(''.join(regex.findall(l[i]))) #adds in the list just the string in the matches2 list


Stored procedure with default parameters

I'd do this one of two ways. Since you're setting your start and end dates in your t-sql code, i wouldn't ask for parameters in the stored proc

Option 1

Create Procedure [Test] AS
    DECLARE @StartDate varchar(10)
    DECLARE @EndDate varchar(10)
    Set @StartDate = '201620' --Define start YearWeek
    Set @EndDate  = (SELECT CAST(DATEPART(YEAR,getdate()) AS varchar(4)) + CAST(DATEPART(WEEK,getdate())-1 AS varchar(2)))

    (SELECT DISTINCT [YEAR],[WeekOfYear] FROM [dbo].[DimDate] WHERE [Year]+[WeekOfYear] BETWEEN @StartDate AND @EndDate ) dimd
    LEFT JOIN [Schema].[Table1] qad ON (qad.[Year]+qad.[Week of the Year]) = (dimd.[Year]+dimd.WeekOfYear)

Option 2

Create Procedure [Test] @StartDate varchar(10),@EndDate varchar(10) AS

    (SELECT DISTINCT [YEAR],[WeekOfYear] FROM [dbo].[DimDate] WHERE [Year]+[WeekOfYear] BETWEEN @StartDate AND @EndDate ) dimd
    LEFT JOIN [Schema].[Table1] qad ON (qad.[Year]+qad.[Week of the Year]) = (dimd.[Year]+dimd.WeekOfYear)

Then run exec test '2016-01-01','2016-01-25'

CSS: How to position two elements on top of each other, without specifying a height?

Due to absolute positioning removing the elements from the document flow position: absolute is not the right tool for the job. Depending on the exact layout you want to create you will be successful using negative margins, position:relative or maybe even transform: translate. Show us a sample of what you want to do we can help you better.

How to know what the 'errno' means?

There's a few useful functions for dealing with errnos. (Just to make it clear, these are built-in to libc -- I'm just providing sample implementations because some people find reading code clearer than reading English.)

#include <string.h>
char *strerror(int errnum);

/* you can think of it as being implemented like this: */
static char strerror_buf[1024];
const char *sys_errlist[] = {
    [EPERM]  = "Operation not permitted",
    [ENOENT] = "No such file or directory",
    [ESRCH]  = "No such process",
    [EINTR]  = "Interrupted system call",
    [EIO]    = "I/O error",
    [ENXIO]  = "No such device or address",
    [E2BIG]  = "Argument list too long",
    /* etc. */
int sys_nerr = sizeof(sys_errlist) / sizeof(char *);
char *strerror(int errnum) {
    if (0 <= errnum && errnum < sys_nerr && sys_errlist[errnum])
        strcpy(strerror_buf, sys_errlist[errnum]);
        sprintf(strerror_buf, "Unknown error %d", errnum);
    return strerror_buf;

strerror returns a string describing the error number you've passed to it. Caution, this is not thread- or interrupt-safe; it is free to rewrite the string and return the same pointer on the next invocation. Use strerror_r if you need to worry about that.

#include <stdio.h>
void perror(const char *s);

/* you can think of it as being implemented like this: */
void perror(const char *s) {
    fprintf(stderr, "%s: %s\n", s, strerror(errno));

perror prints out the message you give it, plus a string describing the current errno, to standard error.

plot different color for different categorical levels using matplotlib

I usually do it using Seaborn which is built on top of matplotlib

import seaborn as sns
iris = sns.load_dataset('iris')
sns.scatterplot(x='sepal_length', y='sepal_width',
              hue='species', data=iris); 

how to convert a string to date in mysql?

STR_TO_DATE('12/31/2011', '%m/%d/%Y')

Tensorflow: how to save/restore a model?

In most cases, saving and restoring from disk using a tf.train.Saver is your best option:

... # build your model
saver = tf.train.Saver()

with tf.Session() as sess:
    ... # train the model, "/tmp/my_great_model")

with tf.Session() as sess:
    saver.restore(sess, "/tmp/my_great_model")
    ... # use the model

You can also save/restore the graph structure itself (see the MetaGraph documentation for details). By default, the Saver saves the graph structure into a .meta file. You can call import_meta_graph() to restore it. It restores the graph structure and returns a Saver that you can use to restore the model's state:

saver = tf.train.import_meta_graph("/tmp/my_great_model.meta")

with tf.Session() as sess:
    saver.restore(sess, "/tmp/my_great_model")
    ... # use the model

However, there are cases where you need something much faster. For example, if you implement early stopping, you want to save checkpoints every time the model improves during training (as measured on the validation set), then if there is no progress for some time, you want to roll back to the best model. If you save the model to disk every time it improves, it will tremendously slow down training. The trick is to save the variable states to memory, then just restore them later:

... # build your model

# get a handle on the graph nodes we need to save/restore the model
graph = tf.get_default_graph()
gvars = graph.get_collection(tf.GraphKeys.GLOBAL_VARIABLES)
assign_ops = [graph.get_operation_by_name( + "/Assign") for v in gvars]
init_values = [assign_op.inputs[1] for assign_op in assign_ops]

with tf.Session() as sess:
    ... # train the model

    # when needed, save the model state to memory
    gvars_state =

    # when needed, restore the model state
    feed_dict = {init_value: val
                 for init_value, val in zip(init_values, gvars_state)}, feed_dict=feed_dict)

A quick explanation: when you create a variable X, TensorFlow automatically creates an assignment operation X/Assign to set the variable's initial value. Instead of creating placeholders and extra assignment ops (which would just make the graph messy), we just use these existing assignment ops. The first input of each assignment op is a reference to the variable it is supposed to initialize, and the second input (assign_op.inputs[1]) is the initial value. So in order to set any value we want (instead of the initial value), we need to use a feed_dict and replace the initial value. Yes, TensorFlow lets you feed a value for any op, not just for placeholders, so this works fine.

python numpy/scipy curve fitting

I suggest you to start with simple polynomial fit, scipy.optimize.curve_fit tries to fit a function f that you must know to a set of points.

This is a simple 3 degree polynomial fit using numpy.polyfit and poly1d, the first performs a least squares polynomial fit and the second calculates the new points:

import numpy as np
import matplotlib.pyplot as plt

points = np.array([(1, 1), (2, 4), (3, 1), (9, 3)])
# get x and y vectors
x = points[:,0]
y = points[:,1]

# calculate polynomial
z = np.polyfit(x, y, 3)
f = np.poly1d(z)

# calculate new x's and y's
x_new = np.linspace(x[0], x[-1], 50)
y_new = f(x_new)

plt.plot(x,y,'o', x_new, y_new)
plt.xlim([x[0]-1, x[-1] + 1 ])

enter image description here

JavaScript - onClick to get the ID of the clicked button

You can simply do it this way:

<input type="button" id="1234" onclick="showId(" value="click me to show my id"/>
<script type="text/javascript">
   function showId(obj) {
        var id=obj;

MVC4 DataType.Date EditorFor won't display date value in Chrome, fine in Internet Explorer

In MVC 3 I had to add:

using System.ComponentModel.DataAnnotations;

among usings when adding properties:

[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]

Especially if you are adding these properties in .edmx file like me. I found that by default .edmx files don't have this using so adding only propeties is not enough.

Why is Git better than Subversion?

I think Subversion is fine.. until you start merging.. or doing anything complicated.. or doing anything Subversion thinks is complicated (like doing queries to find out which branches messed with a particular file, where a change actually comes from, detecting copy&pastes, etc)...

I disagree with the winning answer, saying the main benefit of GIT is offline work - it's certainly useful, but it's more like an extra for my use case. SVK can work offline too, still there is no question for me which one to invest my learning time in).

It's just that it's incredibly powerful and fast and, well -after getting used to the concepts - very useful (yes, in that sense: user friendly).

For more details on a merging story, see this : Using git-svn (or similar) *just* to help out with an svn merge?

How to increase the max upload file size in ASP.NET?

I have a blog post on how to increase the file size for asp upload control.

From the post:

By default, the FileUpload control allows a maximum of 4MB file to be uploaded and the execution timeout is 110 seconds. These properties can be changed from within the web.config file’s httpRuntime section. The maxRequestLength property determines the maximum file size that can be uploaded. The executionTimeout property determines the maximum time for execution.

Convert INT to FLOAT in SQL

In oracle db there is a trick for casting int to float (I suppose, it should also work in mysql):

select myintfield + 0.0 as myfloatfield from mytable

While @Heximal's answer works, I don't personally recommend it.

This is because it uses implicit casting. Although you didn't type CAST, either the SUM() or the 0.0 need to be cast to be the same data-types, before the + can happen. In this case the order of precedence is in your favour, and you get a float on both sides, and a float as a result of the +. But SUM(aFloatField) + 0 does not yield an INT, because the 0 is being implicitly cast to a FLOAT.

I find that in most programming cases, it is much preferable to be explicit. Don't leave things to chance, confusion, or interpretation.

If you want to be explicit, I would use the following.

CAST(SUM( AS FLOAT) * cp.price
-- using MySQL CAST FLOAT  requires 8.0

I won't discuss whether NUMERIC or FLOAT *(fixed point, instead of floating point)* is more appropriate, when it comes to rounding errors, etc. I'll just let you google that if you need to, but FLOAT is so massively misused that there is a lot to read about the subject already out there.

You can try the following to see what happens...

CAST(SUM( AS NUMERIC(10,4)) * CAST(cp.price AS NUMERIC(10,4))

How to get the latest record in each group using GROUP BY?

Just complementing what Devart said, the below code is not ordering according to the question:

SELECT t1.* FROM messages t1
  JOIN (SELECT from_id, MAX(timestamp) timestamp FROM messages GROUP BY from_id) t2
    ON t1.from_id = t2.from_id AND t1.timestamp = t2.timestamp;

The "GROUP BY" clause must be in the main query since that we need first reorder the "SOURCE" to get the needed "grouping" so:

SELECT t1.* FROM messages t1
  JOIN (SELECT from_id, MAX(timestamp) timestamp FROM messages ORDER BY timestamp DESC) t2
    ON t1.from_id = t2.from_id AND t1.timestamp = t2.timestamp GROUP BY t2.timestamp;


React fetch data in server before render

As a supplement of the answer of Michael Parker, you can make getData accept a callback function to active the setState update the data:

componentWillMount : function () {
    var data = this.getData(()=>this.setState({data : data}));

How to get Django and ReactJS to work together?

I know this is a couple of years late, but I'm putting it out there for the next person on this journey.

GraphQL has been helpful and way easier compared to DjangoRESTFramework. It is also more flexible in terms of the responses you get. You get what you ask for and don't have to filter through the response to get what you want.

You can use Graphene Django on the server side and React+Apollo/Relay... You can look into it as that is not your question.

Video 100% width and height

Put the video inside a parent div, and set all to 100% width & height with fill of cover. This will ensure the video isn't distorted and ALWAYS fills the div entirely.

.video-wrapper {
    width: 100%;
    height: 100%;

.video-wrapper video {
    object-fit: cover;
    width: 100%;
    height: 100%;

ElasticSearch, Sphinx, Lucene, Solr, Xapian. Which fits for which usage?

As the creator of ElasticSearch, maybe I can give you some reasoning on why I went ahead and created it in the first place :).

Using pure Lucene is challenging. There are many things that you need to take care for if you want it to really perform well, and also, its a library, so no distributed support, it's just an embedded Java library that you need to maintain.

In terms of Lucene usability, way back when (almost 6 years now), I created Compass. Its aim was to simplify using Lucene and make everyday Lucene simpler. What I came across time and time again is the requirement to be able to have Compass distributed. I started to work on it from within Compass, by integrating with data grid solutions like GigaSpaces, Coherence, and Terracotta, but it's not enough.

At its core, a distributed Lucene solution needs to be sharded. Also, with the advancement of HTTP and JSON as ubiquitous APIs, it means that a solution that many different systems with different languages can easily be used.

This is why I went ahead and created ElasticSearch. It has a very advanced distributed model, speaks JSON natively, and exposes many advanced search features, all seamlessly expressed through JSON DSL.

Solr is also a solution for exposing an indexing/search server over HTTP, but I would argue that ElasticSearch provides a much superior distributed model and ease of use (though currently lacking on some of the search features, but not for long, and in any case, the plan is to get all Compass features into ElasticSearch). Of course, I am biased, since I created ElasticSearch, so you might need to check for yourself.

As for Sphinx, I have not used it, so I can't comment. What I can refer you is to this thread at Sphinx forum which I think proves the superior distributed model of ElasticSearch.

Of course, ElasticSearch has many more features than just being distributed. It is actually built with a cloud in mind. You can check the feature list on the site.

How to compare data between two table in different databases using Sql Server 2008?

I'v done things like this using the Checksum(*) function

In essance it creates a row level checksum on all the columns data, you could then compare the checksum of each row for each table to each other, use a left join, to find rows that are different.

Hope that made sense...

Better with an example....

select *
( select checksum(*) as chk, userid as k from UserAccounts) as t1
left join 
( select checksum(*) as chk, userid as k from UserAccounts) as t2 on t1.k = t2.k
where t1.chk <> t2.chk 

Java maximum memory on Windows XP

This has to do with contiguous memory.

Here's some info I found online for somebody asking that before, supposedly from a "VM god":

The reason we need a contiguous memory region for the heap is that we have a bunch of side data structures that are indexed by (scaled) offsets from the start of the heap. For example, we track object reference updates with a "card mark array" that has one byte for each 512 bytes of heap. When we store a reference in the heap we have to mark the corresponding byte in the card mark array. We right shift the destination address of the store and use that to index the card mark array. Fun addressing arithmetic games you can't do in Java that you get to (have to :-) play in C++.

Usually we don't have trouble getting modest contiguous regions (up to about 1.5GB on Windohs, up to about 3.8GB on Solaris. YMMV.). On Windohs, the problem is mostly that there are some libraries that get loaded before the JVM starts up that break up the address space. Using the /3GB switch won't rebase those libraries, so they are still a problem for us.

We know how to make chunked heaps, but there would be some overhead to using them. We have more requests for faster storage management than we do for larger heaps in the 32-bit JVM. If you really want large heaps, switch to the 64-bit JVM. We still need contiguous memory, but it's much easier to get in a 64-bit address space.


Sometimes even the simplest things can make a difference. One of these simple items that should be part of every stored procedure is SET NOCOUNT ON. This one line of code, put at the top of a stored procedure turns off the messages that SQL Server sends back to the client after each T-SQL statement is executed. This is performed for all SELECT, INSERT, UPDATE, and DELETE statements. Having this information is handy when you run a T-SQL statement in a query window, but when stored procedures are run there is no need for this information to be passed back to the client.

By removing this extra overhead from the network it can greatly improve overall performance for your database and application.

If you still need to get the number of rows affected by the T-SQL statement that is executing you can still use the @@ROWCOUNT option. By issuing a SET NOCOUNT ON this function (@@ROWCOUNT) still works and can still be used in your stored procedures to identify how many rows were affected by the statement.

Get all object attributes in Python?

What you probably want is dir().

The catch is that classes are able to override the special __dir__ method, which causes dir() to return whatever the class wants (though they are encouraged to return an accurate list, this is not enforced). Furthermore, some objects may implement dynamic attributes by overriding __getattr__, may be RPC proxy objects, or may be instances of C-extension classes. If your object is one these examples, they may not have a __dict__ or be able to provide a comprehensive list of attributes via __dir__: many of these objects may have so many dynamic attrs it doesn't won't actually know what it has until you try to access it.

In the short run, if dir() isn't sufficient, you could write a function which traverses __dict__ for an object, then __dict__ for all the classes in obj.__class__.__mro__; though this will only work for normal python objects. In the long run, you may have to use duck typing + assumptions - if it looks like a duck, cross your fingers, and hope it has .feathers.

How to find the kafka version in linux

Kafka 2.0 have the fix(KIP-278) for it: --version

Using confluent utility:

Kakfa version check can be done with confluent utility which comes by default with Confluent platform(confluent utility can be added to cluster separately as well - credits cricket_007).

${confluent.home}/bin/confluent version kafka

Checking the version of other Confluent platform components like ksql schema-registry and connect

[confluent-4.1.0]$ ./bin/confluent version kafka

[confluent-4.1.0]$ ./bin/confluent version connect

[confluent-4.1.0]$ ./bin/confluent version schema-registry

[confluent-4.1.0]$ ./bin/confluent version ksql-server

How to remove white space characters from a string in SQL Server

Remove new line characters with SQL column data

Update a set  a.CityName=Rtrim(Ltrim(REPLACE(REPLACE(a.CityName,CHAR(10),' '),CHAR(13),' ')))
,a.postalZone=Rtrim(Ltrim(REPLACE(REPLACE(a.postalZone,CHAR(10),' '),CHAR(13),' ')))  
From tAddress a 
inner Join  tEmployees p  on a.AddressId =p.addressId 
Where p.MigratedID is not null and p.AddressId is not null AND
(REPLACE(REPLACE(a.postalZone,CHAR(10),'Y'),CHAR(13),'X') Like 'Y%' OR REPLACE(REPLACE(a.CityName,CHAR(10),'Y'),CHAR(13),'X') Like 'Y%')

How to set combobox default value?

You can do something like this:

    public myform()
         InitializeComponent(); // this will be called in ComboBox ComboBox = new System.Windows.Forms.ComboBox();

    private void Form1_Load(object sender, EventArgs e)
        // TODO: This line of code loads data into the 'myDataSet.someTable' table. You can move, or remove it, as needed.
        comboBox1.SelectedItem = null;
        comboBox1.SelectedText = "--select--";           

json.decoder.JSONDecodeError: Extra data: line 2 column 1 (char 190)

I was parsing JSON from a REST API call and got this error. It turns out the API had become "fussier" (eg about order of parameters etc) and so was returning malformed results. Check that you are getting what you expect :)

How to draw a rectangle around a region of interest in python

please don't try with the old cv module, use cv2:

import cv2

cv2.rectangle(img, (x1, y1), (x2, y2), (255,0,0), 2)

x1,y1 ------
|          |
|          |
|          |

[edit] to append the follow-up questions below:


cv2.imshow("lalala", img)
k = cv2.waitKey(0) # 0==wait forever

Clear android application user data

If you want to do manually then You also can clear your user data by clicking “Clear Data” button in Settings–>Applications–>Manage Aplications–> YOUR APPLICATION

or Is there any other way to do that?

Then Download code here

enter image description here

What is Persistence Context?

A persistence context handles a set of entities which hold data to be persisted in some persistence store (e.g. a database). In particular, the context is aware of the different states an entity can have (e.g. managed, detached) in relation to both the context and the underlying persistence store.

Although Hibernate-related (a JPA provider), I think these links are useful:

In Java EE, a persistence context is normally accessed via an EntityManager.

The various states an entity can have and the transitions between these are described below:

How to kill zombie process

A zombie is already dead, so you cannot kill it. To clean up a zombie, it must be waited on by its parent, so killing the parent should work to eliminate the zombie. (After the parent dies, the zombie will be inherited by pid 1, which will wait on it and clear its entry in the process table.) If your daemon is spawning children that become zombies, you have a bug. Your daemon should notice when its children die and wait on them to determine their exit status.

An example of how you might send a signal to every process that is the parent of a zombie (note that this is extremely crude and might kill processes that you do not intend. I do not recommend using this sort of sledge hammer):

# Don't do this.  Incredibly risky sledge hammer!
kill $(ps -A -ostat,ppid | awk '/[zZ]/ && !a[$2]++ {print $2}')

How do I set a background-color for the width of text, not the width of the entire element, using CSS?

EDIT: the answer below would apply in most cases. OP however later mentioned that they could not edit anything other than the CSS file. But will leave this here so it may be of use to others.

enter image description here

The main consideration that others are neglecting is that OP has stated that they cannot modify the HTML.

You can target what you need in the DOM then add classes dynamically with javascript. Then style as you need.

In an example that I made, I targeted all <p> elements with jQuery and wrapped it with a div with a class of "colored"

$( "p" ).wrap( "<div class='colored'></div>" );

Then in my CSS i targeted the <p> and gave it the background color and changed to display: inline

.colored p {
    display: inline;
    background: green;

By setting the display to inline you lose some of the styling that it would normally inherit. So make sure that you target the most specific element and style the container to fit the rest of your design. This is just meant as a working starting point. Use carefully. Working demo on CodePen

private final static attribute vs private final attribute

In general, static means "associated with the type itself, rather than an instance of the type."

That means you can reference a static variable without having ever created an instances of the type, and any code referring to the variable is referring to the exact same data. Compare this with an instance variable: in that case, there's one independent version of the variable per instance of the class. So for example:

Test x = new Test();
Test y = new Test();
x.instanceVariable = 10;
y.instanceVariable = 20;

prints out 10: y.instanceVariable and x.instanceVariable are separate, because x and y refer to different objects.

You can refer to static members via references, although it's a bad idea to do so. If we did:

Test x = new Test();
Test y = new Test();
x.staticVariable = 10;
y.staticVariable = 20;

then that would print out 20 - there's only one variable, not one per instance. It would have been clearer to write this as:

Test x = new Test();
Test y = new Test();
Test.staticVariable = 10;
Test.staticVariable = 20;

That makes the behaviour much more obvious. Modern IDEs will usually suggest changing the second listing into the third.

There is no reason to have an inline declaration initializing the value like the following, as each instance will have its own NUMBER but always with the same value (is immutable and initialized with a literal). This is the same than to have only one final static variable for all instances.

private final int NUMBER = 10;

Therefore if it cannot change, there is no point having one copy per instance.

But, it makes sense if is initialized in a constructor like this:

// No initialization when is declared
private final int number;

public MyClass(int n) {
   // The variable can be assigned in the constructor, but then
   // not modified later.
   number = n;

Now, for each instance of MyClass, we can have a different but immutable value of number.

Click to call html

tl;dr What to do in modern (2018) times? Assume tel: is supported, use it and forget about anything else.

The tel: URI scheme RFC5431 (as well as sms: but also feed:, maps:, youtube: and others) is handled by protocol handlers (as mailto: and http: are).

They're unrelated to HTML5 specification (it has been out there from 90s and documented first time back in 2k with RFC2806) then you can't check for their support using tools as modernizr. A protocol handler may be installed by an application (for example Skype installs a callto: protocol handler with same meaning and behaviour of tel: but it's not a standard), natively supported by browser or installed (with some limitations) by website itself.

What HTML5 added is support for installing custom web based protocol handlers (with registerProtocolHandler() and related functions) simplifying also the check for their support through isProtocolHandlerRegistered() function.

There is some easy ways to determine if there is an handler or not:" How to detect browser's protocol handlers?).

In general what I suggest is:

  1. If you're running on a mobile device then you can safely assume tel: is supported (yes, it's not true for very old devices but IMO you can ignore them).
  2. If JS isn't active then do nothing.
  3. If you're running on desktop browsers then you can use one of the techniques in the linked post to determine if it's supported.
  4. If tel: isn't supported then change links to use callto: and repeat check desctibed in 3.
  5. If tel: and callto: aren't supported (or - in a desktop browser - you can't detect their support) then simply remove that link replacing URL in href with javascript:void(0) and (if number isn't repeated in text span) putting, telephone number in title. Here HTML5 microdata won't help users (just search engines). Note that newer versions of Skype handle both callto: and tel:.

Please note that (at least on latest Windows versions) there is always a - fake - registered protocol handler called App Picker (that annoying window that let you choose with which application you want to open an unknown file). This may vanish your tests so if you don't want to handle Windows environment as a special case you can simplify this process as:

  1. If you're running on a mobile device then assume tel: is supported.
  2. If you're running on desktop then replace tel: with callto:. then drop tel: or leave it as is (assuming there are good chances Skype is installed).

Hide axis values but keep axis tick labels in matplotlib


enter image description here

How to remove the default link color of the html hyperlink 'a' tag?

You can use System Color (18.2) values, introduced with CSS 2.0, but deprecated in CSS 3.

a:link, a:hover, a:active { color: WindowText; }

That way your anchor links will have the same color as normal document text on this system.

How to set label size in Bootstrap

You'll have to do 2 things to make a Bootstrap label (or anything really) adjust sizes based on screen size:

  • Use a media query per display size range to adjust the CSS.
  • Override CSS sizing set by Bootstrap. You do this by making your CSS rules more specific than Bootstrap's. By default, Bootstrap sets .label { font-size: 75% }. So any extra selector on your CSS rule will make it more specific.

Here's an example CSS listing to accomplish what you are asking, using the default 4 sizes in Bootstrap:

@media (max-width: 767) {
    /* your custom css class on a parent will increase specificity */
    /* so this rule will override Bootstrap's font size setting */
    .autosized .label { font-size: 14px; }

@media (min-width: 768px) and (max-width: 991px) {
    .autosized .label { font-size: 16px; }

@media (min-width: 992px) and (max-width: 1199px) {
    .autosized .label { font-size: 18px; }

@media (min-width: 1200px) {
    .autosized .label { font-size: 20px; }

Here is how it could be used in the HTML:

<!-- any ancestor could be set to autosized -->
<div class="autosized">
            <span class="label label-primary">Label 1</span>

How to check for an active Internet connection on iOS or macOS?

- (void)viewWillAppear:(BOOL)animated
    NSString *URL = [NSString stringWithContentsOfURL:[NSURL URLWithString:@""]];

    return (URL != NULL ) ? YES : NO;

Or use the Reachability class.

There are two ways to check Internet availability using the iPhone SDK:

1. Check the Google page is opened or not.

2. Reachability Class

For more information, please refer to Reachability (Apple Developer).

Is there Java HashMap equivalent in PHP?

Arrays in PHP can have Key Value structure.

HTML table with 100% width, with vertical scroll inside tbody

This is the code that works for me to create a sticky thead on a table with a scrollable tbody:

table ,tr td{
    border:1px solid red
tbody {
thead, tbody tr {
    table-layout:fixed;/* even columns width , fix width of table too*/
thead {
    width: calc( 100% - 1em )/* scrollbar is average 1em/16px width, remove it from thead width */
table {

Convert array of integers to comma-separated string

var result = string.Join(",", arr);

This uses the following overload of string.Join:

public static string Join<T>(string separator, IEnumerable<T> values);

How do I rewrite URLs in a proxy response in NGINX

You may also need the following directive to be set before the first "sub_filter" for backend-servers with data compression:

proxy_set_header Accept-Encoding "";

Otherwise it may not work. For your example it will look like:

location /admin/ {
    proxy_pass http://localhost:8080/;
    proxy_set_header Accept-Encoding "";
    sub_filter "http://your_server/" "http://your_server/admin/";
    sub_filter_once off;

stringstream, string, and char* conversion confusion

The std::string object returned by ss.str() is a temporary object that will have a life time limited to the expression. So you cannot assign a pointer to a temporary object without getting trash.

Now, there is one exception: if you use a const reference to get the temporary object, it is legal to use it for a wider life time. For example you should do:

#include <string>
#include <sstream>
#include <iostream>

using namespace std;

int main()
    stringstream ss("this is a string\n");

    string str(ss.str());

    const char* cstr1 = str.c_str();

    const std::string& resultstr = ss.str();
    const char* cstr2 = resultstr.c_str();

    cout << cstr1       // Prints correctly
        << cstr2;       // No more error : cstr2 points to resultstr memory that is still alive as we used the const reference to keep it for a time.


    return 0;

That way you get the string for a longer time.

Now, you have to know that there is a kind of optimisation called RVO that say that if the compiler see an initialization via a function call and that function return a temporary, it will not do the copy but just make the assigned value be the temporary. That way you don't need to actually use a reference, it's only if you want to be sure that it will not copy that it's necessary. So doing:

 std::string resultstr = ss.str();
 const char* cstr2 = resultstr.c_str();

would be better and simpler.

Running a Python script from PHP

If you want to know the return status of the command and get the entire stdout output you can actually use exec:

$command = 'ls';
exec($command, $out, $status);

$out is an array of all lines. $status is the return status. Very useful for debugging.

If you also want to see the stderr output you can either play with proc_open or simply add 2>&1 to your $command. The latter is often sufficient to get things working and way faster to "implement".

How to add header data in XMLHttpRequest when using formdata?

Your error

InvalidStateError: An attempt was made to use an object that is not, or is no longer, usable

appears because you must call setRequestHeader after calling open. Simply move your setRequestHeader line below your open line (but before send):"POST", url);
xmlhttp.setRequestHeader("x-filename", photoId);